1. Field of the Invention
The present invention relates to the process of preparing tertiarybutylbis-(dimethylamino)phosphine, ((CH.sub.3).sub.3 C)((CH.sub.3).sub.2 N).sub.2 P, and its use in chemical vapor deposition processes to produce phosphorus-containing semiconductor materials.
Currently, there is a need for an alternative organophosphorus precursor semiconductor material without substituents, which results in unintentional carbon incorporation for low temperature Organometallic Vapor Phase Epitaxy (hereinafter, OMVPE) and Chemical Beam Epitaxy (hereinafter, CBE). The availability of alternative OMVPE and CBE organophosphorus precursors with lower pyrolysis temperatures and lower carbon incorporation characteristics would greatly enhance the development of phosphorus containing semiconductor materials and devices. This invention addresses this need of formulating an alternative phosphorus-containing semiconductor material.
2. Description of the Prior Art
A variety of semiconductor systems containing phosphorus have been investigated for applications in electronic and optoelectronic devices (e.g. light-emitting diodes and lasers). Phosphorus containing binary materials, Indium Phosphide (hereinafter, InP) Gallium Phosphide (hereinafter, GaP), as well as ternary and quaternary materials, (e.g. GaP.sub.1-x Sb.sub.x, InP.sub.1-x Sb.sub.x, In.sub.1-x Ga.sub.x P, Ga.sub.1-x Al.sub.x P, Al.sub.1-(x+y) Ga.sub.x In.sub.y P, In.sub.1-x P.sub.x As.sub.1-y Sb.sub.y and Ga.sub.1-x In.sub.x As.sub.1-y P.sub.y), have been grown heteroepitaxially by OMVPE and CBE techniques for the production of high quality semiconductor materials from organometallic precursors such as organophosphorus compounds.
Certain semiconductor materials have been grown by OMVPE and CBE using tertiarybutylphosphine (hereinafter, TBP) as the organophosphorus source compound. For CBE growth of phosphorus-containing semiconductor materials the phosphorus precursor compound is pyrolyzed in a high temperature cracker cell prior to contact with the heated substrate. The cracker cell temperature is critical for InP growth by CBE using TBP. Excessively high cracker cell temperature increases unintentional carbon incorporation. Attempts at low growth temperature in OMVPE or growth without the use of a high temperature cracker cell in CBE results in significant problems due to the incomplete pyrolysis of the organophosphorus compound.
An alternative organophosphorus precursor for OMVPE and CBE is needed which has a lower pyrolysis temperature than TBP. An important requirement for the organophosphorus precursor is that it must pyrolyze with minimal unintentional impurity incorporation. The availability of alternative phosphorus (hereinafter, P) source compounds for OMVPE and CBE would greatly enhance the development of phosphorus-containing semiconductor materials. Development of new P source compounds for chemical vapor deposition processes is of much interest. These compounds would eliminate the need for lowering the cracker cell temperature or film-growth temperature of P-containing semiconductor materials and also would eliminate the need to alter the chemistry to minimize unintentional impurities.